Appreciate this very much. I saw the NYT article, then saw a famous climate scientist holding forth on Bluesky about his dim view of acceleration. Naturally, I went to Forster's website and read his take. But, I really needed a comprehensive view.
That famous scientist also stuck religiously to the slowdown or hiatus view (and even co-authored a paper to that effect, IIRC) but eventually was forced (by overwhelming evidence) to admit that there really was no slowdown. I don't think he ever acknowledged that he changed his mind.
Fitting linear trends is always a very bad thing to do because it emphasizes the end points. Besides, given the changing climate there is no reason at all for anything to be linear. It is reasonable before about 1970 to fit a linear trend, as has been shown many places, but then acceleration upwards is mandatory. The question should be has it stopped? Indeed, once again water vapor feedback is ignored. It can only kick in as temperatures rise and an assessment indicates the net forcing matches or even exceeds that of CO2 increases since 1970. But it is a feedback, one of many. Ice-albedo feedback is another obvious one. That will cease when all the ice is gone!
There are indeed issues with EEI. The last points are very ordinary, highlighting variability. And the first 3 years are too low as that was when there was only one satellite. So the trend is slightly inflated. In any case it is caused mostly by changes in atmospheric and ocean circulation as the tropics (down branch Hadley) get wider and storm tracks and the jet streams over the oceans move polewards.
Given that emissions keep rising, natural carbon sinks are becoming less efficient, and cooling aerosols are decreasing, it would be surprising if warning wasn't accelerating.
There are plenty of good estimates of emissions impacts, but it won't really show up noticeably in global temperatures in the near-term given the magnitudes of emissions involved.
Is Trump much different from Democrats? Has Trump actually cut back on renewable expansion or is it like other threats?
Would it make any difference anyway? Renewables are just an energy addition- Biden was still backing new fossil fuels, producing LNG and doing nothing to cut back on animal ag.
Do you mind elaborating on the EEI point? The rise in EEI is shockingly high, as you noted. If we nail down that value with certainty, does that conclusively prove that ECS is high (more in the range of what Hansen would predict)?
However, there is only a loose correlation between model ECS and EEI over the past decade or two, so while it suggests an ECS >2.5C its hard to use it for a precise constraint.
Thanks that makes sense. If the EEI keeps growing at this rapid rate (say, another decade), am I right to assume that the correlation between ECS and EEI will be stronger? I guess I am wondering why we wouldn’t see the EEI accelerate further if the drivers of that acceleration (either aerosol reductions of reduced cloud cover) continue to follow recent trends. Recent papers tracking reduced cloud reflectivity are especially alarming.
Considering the number of positive feedbacks, both in terms of natural emission sources (and sinks) and reduction in albedo, isn't acceleration the null hypothesis?
Even considering carbon sinks and feedbacks, we'd expect a pretty linear relationship between cumulative emissions and warming. What has changed notably in recent years is aerosol forcings.
Mmmm … there's an interesting way I devised to look at this. For each year in the dataset, calculate the acceleration of the previous X number of years and plot that as a data point. Here's the result.
I'm not a climatologist and don't have enough command of quantitative methods to even pretend to be. But I been playing around with the idea of a punctuated equilibrium model similar to the revolutionary biology proposed by Jay Gould et al. Briefly periods of relative stability punctuated by short periods of rapid change. I think that what we might be seeing is that the plateaus are getting shorter and the rapid increases are getting more frequent. Graphed out it would be a stair-step with the platforms getting shorter and the risers getting higher. Smoothed, it would show a steep curve of acceleration. Of course either global graph would be the product of a million local graphs all proceeding differently. I doubt it's within our current exa-scale computers capacities to calculate a true global prediction more than a couple of years out, if that
Those piece-wise linear and change-point models sound odd. If we want to see if there is evidence of acceleration, I'd fit a model with change (linear), plus change of change (quadratic), and look at the posterior of the coefficient of the latter term. Of course, natural variation and other things to be controlled would be in the same model. This is trivial enough, so someone has done it?
Although if after all the "natural variation" controlled, if there is still a reason to assume autocorrelation structure there to be taken into the same model, things would get muddy and complicated, and results likely less clear.
On the other hand, acceleration should be obvious given increasing CO2 etc. Acceleration more than reasonable or jumps are more interesting. Operationalizing them into a model for sure would cause discussions.
I look at the "Drivers of Decadal Warming" graph and wonder, "Since not dumping aerosols into the atmosphere is, in general, a good thing, would doing simply things like painting all our roofs white help do what the aerosols did?" I'm a clergy person, not a scientist, still, that's where my mind goes.
Well, sulfur dioxide and other PM2.5 precursors contribute to ~8 million premature deaths per year. And most SO2 is co-emitted with CO2 from fossil fuel combustion. So reducing it is generally a good thing, unmasking of historical warming notwithstanding.
Appreciate this very much. I saw the NYT article, then saw a famous climate scientist holding forth on Bluesky about his dim view of acceleration. Naturally, I went to Forster's website and read his take. But, I really needed a comprehensive view.
That famous scientist also stuck religiously to the slowdown or hiatus view (and even co-authored a paper to that effect, IIRC) but eventually was forced (by overwhelming evidence) to admit that there really was no slowdown. I don't think he ever acknowledged that he changed his mind.
Fitting linear trends is always a very bad thing to do because it emphasizes the end points. Besides, given the changing climate there is no reason at all for anything to be linear. It is reasonable before about 1970 to fit a linear trend, as has been shown many places, but then acceleration upwards is mandatory. The question should be has it stopped? Indeed, once again water vapor feedback is ignored. It can only kick in as temperatures rise and an assessment indicates the net forcing matches or even exceeds that of CO2 increases since 1970. But it is a feedback, one of many. Ice-albedo feedback is another obvious one. That will cease when all the ice is gone!
There are indeed issues with EEI. The last points are very ordinary, highlighting variability. And the first 3 years are too low as that was when there was only one satellite. So the trend is slightly inflated. In any case it is caused mostly by changes in atmospheric and ocean circulation as the tropics (down branch Hadley) get wider and storm tracks and the jet streams over the oceans move polewards.
Given that emissions keep rising, natural carbon sinks are becoming less efficient, and cooling aerosols are decreasing, it would be surprising if warning wasn't accelerating.
Not only are atmospheric carbon levels glutting natural carbon sinks, we're actively removing some others.
SETI needs to update their Drake equation.
Been thinking the same thing. Is this another "Great Filter?"
No, just more proof of the fragility of a civilization that can't scale beyond its evolutionary history.
Good observations
Is there enough data to estimate the climate impact of Trump administration policies to halt all US efforts to mitigate climate change?
There are plenty of good estimates of emissions impacts, but it won't really show up noticeably in global temperatures in the near-term given the magnitudes of emissions involved.
Is Trump much different from Democrats? Has Trump actually cut back on renewable expansion or is it like other threats?
Would it make any difference anyway? Renewables are just an energy addition- Biden was still backing new fossil fuels, producing LNG and doing nothing to cut back on animal ag.
Do you mind elaborating on the EEI point? The rise in EEI is shockingly high, as you noted. If we nail down that value with certainty, does that conclusively prove that ECS is high (more in the range of what Hansen would predict)?
EEI is definitely on the high end (or higher than) predictions by climate models, as discussed by Myhre et al in their recent paper: https://www.science.org/doi/10.1126/science.adt0647
However, there is only a loose correlation between model ECS and EEI over the past decade or two, so while it suggests an ECS >2.5C its hard to use it for a precise constraint.
Thanks that makes sense. If the EEI keeps growing at this rapid rate (say, another decade), am I right to assume that the correlation between ECS and EEI will be stronger? I guess I am wondering why we wouldn’t see the EEI accelerate further if the drivers of that acceleration (either aerosol reductions of reduced cloud cover) continue to follow recent trends. Recent papers tracking reduced cloud reflectivity are especially alarming.
Yes, a continued multidecadal trend in EEI would likely be a stronger constraint on climate sensitivity.
Yes , a discussion of the margins of error of both ocean-heat-content increase-rate and EEI would be greatly appreciated!
Considering the number of positive feedbacks, both in terms of natural emission sources (and sinks) and reduction in albedo, isn't acceleration the null hypothesis?
Even considering carbon sinks and feedbacks, we'd expect a pretty linear relationship between cumulative emissions and warming. What has changed notably in recent years is aerosol forcings.
How does that compare to the atmospheric methane increase that suspiciously occurred at the same time as fracking boom?
Mmmm … there's an interesting way I devised to look at this. For each year in the dataset, calculate the acceleration of the previous X number of years and plot that as a data point. Here's the result.
https://rosebyanyothernameblog.wordpress.com/wp-content/uploads/2025/06/fifty-year-accel-ballts.png
Fifty-year trailing acceleration peaked at the 50-year period ending in mid-1991 and has decreased greatly since.
Best to all,
w.
I'm not a climatologist and don't have enough command of quantitative methods to even pretend to be. But I been playing around with the idea of a punctuated equilibrium model similar to the revolutionary biology proposed by Jay Gould et al. Briefly periods of relative stability punctuated by short periods of rapid change. I think that what we might be seeing is that the plateaus are getting shorter and the rapid increases are getting more frequent. Graphed out it would be a stair-step with the platforms getting shorter and the risers getting higher. Smoothed, it would show a steep curve of acceleration. Of course either global graph would be the product of a million local graphs all proceeding differently. I doubt it's within our current exa-scale computers capacities to calculate a true global prediction more than a couple of years out, if that
Those piece-wise linear and change-point models sound odd. If we want to see if there is evidence of acceleration, I'd fit a model with change (linear), plus change of change (quadratic), and look at the posterior of the coefficient of the latter term. Of course, natural variation and other things to be controlled would be in the same model. This is trivial enough, so someone has done it?
Although if after all the "natural variation" controlled, if there is still a reason to assume autocorrelation structure there to be taken into the same model, things would get muddy and complicated, and results likely less clear.
On the other hand, acceleration should be obvious given increasing CO2 etc. Acceleration more than reasonable or jumps are more interesting. Operationalizing them into a model for sure would cause discussions.
I look at the "Drivers of Decadal Warming" graph and wonder, "Since not dumping aerosols into the atmosphere is, in general, a good thing, would doing simply things like painting all our roofs white help do what the aerosols did?" I'm a clergy person, not a scientist, still, that's where my mind goes.
Why not increase the aerosol emissions? Doesn't this mechanism of acceleration suggest a bandaid fix to decelerate?
Well, sulfur dioxide and other PM2.5 precursors contribute to ~8 million premature deaths per year. And most SO2 is co-emitted with CO2 from fossil fuel combustion. So reducing it is generally a good thing, unmasking of historical warming notwithstanding.
Insert "Very long sigh."